Seismic monitoring of alpine lake ice with distributed acoustic sensing (DAS) and nodal arrays

Lake ice stability is critical for safe operations on mid- to high-altitude Alpine lakes, such as touristic activities. Existing lake-ice monitoring approaches like ground-penetrating radar and drilling are limited in their ability to resolve spatial variability and to enable continuous monitoring and require direct access to the ice for in situ measurements. Seismological methods offer a complementary approach by recording the wave field generated by lake-ice flexure and fracturing. Here, we assess Distributed Acoustic Sensing (DAS) as a long-term seismic monitoring tool for Alpine lakes.

During Winter 2025, we deployed two complementary seismic sensing systems on frozen Lake Sankt Moritz in the Swiss Alps: a fibre-optic network for DAS measurements and an array of over 40 three-component conventional autonomous seismic nodes to benchmark performance. We installed more than 2 km of fibre-optic cable and connected two interrogators that recorded, over a few weeks, strain and strain-rate data in two cores within the same cable.

To characterise ice properties and icequakes, we implemented workflows for automated icequake detection and location using the waveform-coherency based QuakeMigrate framework, which does not require phase picking, alongside an approach based on semi-automatic phase identification and picking. We successfully detected and located events with both types of instrument networks. Using a baseline catalogue from the three-component node data, we evaluated the DAS performance and achieved location agreement within a few metres between different sensing systems, demonstrating that DAS can robustly capture and localise icequake activity on lake ice and is a promising tool for continuous ice-stability monitoring.